How to limit VRAM usage for Blender?
Q: Is there a way to limit the amount of VRAM blender uses?

A: NO

Example: if your scene need 2GB of VRAM, Blender need 2GB VRAM for render this scene. No other way. Imagine, you want to pour 2l water into 1.5l bottle.

Also there are no direct evidence the problem is amount of VRAM.
I don't thing VNC need VRAM for running. This doesn't make sense:-)